Elastic and Nonelastic Neutron Cross Sections for Beryllium

Abstract

A time-of-flight technique has been used to measure angular distributions for the elastic scattering of neutrons from beryllium in the energy range from 2.6 to 6.0 Mev. Total neutron cross sections were also measured and the following nonelastic (total minus elastic) cross sections obtained: 2.60 Mev (0.27±0.13 barn), 3.50 (0.43=b0.10), 4.10 (0.51=fc0.08), 5.00 (0.60=b0.08), and 6.00 (0.73=b0.07). Differential cross sections were also obtained for the inelastic neutrons leaving Be 9 in the 2.43-Mev excited state. Integration of these angular distributions yielded the following inelastic cross sections: 3.50 Mev (0.23±0.04 barn), 4.10 (0.25±0.04), and 5.00 (0.34dz0.05). A continuous spectrum of neutrons was observed which corresponds to the direct (n,2n) reaction and/or the excitation of the Be 9 "level" at 1.7 Mev. This continuum was found to have an angular distribution roughly symmetric about 90°. The 2.43-Mev state of Be 9 was found to decay by neutron emission to the ground state of Be 8 with a branching ratio of 12±5%.

Development of a Science Demonstration Laboratory in National University of Singapore

“…The use of boron would be unfavourable due to its high neutron absorption cross section of 749 barns [16,38], which would have absorbed the neutrons much faster than bismuth atoms and thus cause the chain reaction to fail. Between beryllium and fluorine, beryllium was chosen due to its markedly higher (α,n) reaction yield [39]. Atoms of bismuth-209 and beryllium-9 are also able to undergo neutron multiplication reactions such as the (n,2n) reaction to sustain the thermal neutron population in the reaction mixture [6,40,41].…”

Reaction Cross Section Calculations in Neutron Induced Reactions and GEANT4 Simulation of Hadronic Interactions for the Reactor Moderator Material BeO

“…The experimental and theoretical results of 9 Be(n,t) 7 Li and 16 O(n,t) 14 N reactions have been given in Fig. 3 (a) and (b).…”

Evaluation of Be and Li cross section data up to 200 MeV

“…At first, the parameters for 9 Be are searched because the number of experimental data for Be is larger than that for Li isotopes. Figure 1 shows neutron incident total [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] (upper left), nonelastic [11,17,[27][28][29][30][31][32][33][34][35][36][37][38][39][40][41] (upper right), elastic cross sections [17,19,27,33,[42][43][44][45][46][47][48][49][50][51]…”